Cirrus

GID Urban Development Acquisitions, LLC
Seattle, Washington

Cirrus highrise

Hart Crowser provided geotechnical design for a forty-story highrise development at Eighth and Lenora on a quarter of a block at 2030 8th Avenue in downtown Seattle. The building has five levels of underground parking. Challenges included excavating below the foundation levels of adjacent buildings and underpinning adjacent structures. This area has varying levels of fill from the Denny Regrade project in the early 1900s, when Denny Hill was cut down and portions of it were placed in the valley that ran along Westlake Avenue. Seismic components included evaluating basin effects and incorporating them into the design recommendations; developing site-specific design response spectra for two hazard levels; and providing spectrum-compatible earthquake ground motion pairs for input to the 3D structural analysis.